Method of manufacturing modified wood material

Abstract

A method of manufacturing a modifed wood material can fix within a raw wood material an insoluble, non-flammable inorganic compound with a highly efficient reaction achieved between cations and anions by sequentially immersing the raw wood material at least three times alternately in each of, and different one from that employed immediately before of a first water-soluble inorganic substance solution containing cations and a second water-soluble inorganic substance solution containing anions.

What we claim as our invention is: 
     
       1. A method for making a modified wood material, comprising alternately immersing a raw wood material in two types of solutions, a cation-containing solution and an anion-containing solution, the cations and anions being such as to form a non-flammable, water-insoluble, inorganic compound within the raw wood material, wherein said raw wood material is alternately immersed a total of at least three times in one of said two types of solutions and then in the other of said two types of solution and wherein the solution employed for the third immersing is made higher in concentration than that used for the first immersing. 
     
     
       2. A method according to claim 1, wherein said cation-containing solution includes at least one cation selected from the group consisting of magnesium, aluminum, calcium, zinc and barium ions, and said anion-containing solution includes at least one anion selected from the group consisting of carbonic acid ions, silicic acid ions, sulfuric acid ions, phosphoric acid ions, boric acid ions and hydroxide ions. 
     
     
       3. A method according to claim 1, wherein a first one of the three total immersings is carried out under vacuum. 
     
     
       4. A method according to claim 1, wherein the solutions used for the first and third immersings are of the same ions. 
     
     
       5. A method according to claim 4, wherein an anion-containing solution is used for the first and third immersing. 
     
     
       6. A method according to claim 1, wherein at least one of said two types of solutions contains at least one member selected from the group consisting of boric acid and sodium borate. 
     
     
       7. A method according to claim 1, wherein said two types of solutions are prepared with water-soluble inorganic substances the solubility of which is selected to be more than 5 g with respect to 100 g of water at 25° C.